In recent years, chip-type electronic parts such as IC chips and capacitors have been stored in embossed portions of carrier tape formed consecutively at regular intervals, then transported and kept in storage as tape packages heat sealed with cover tape. When mounting the electronic parts stored in the tape packages on electronic circuit boards, the cover tape is continuously stripped at a high speed while the electronic parts are taken out one by one.
When using such tape packages, static electricity can be generated during transport and storage by the friction or contact between the electronic parts stored in the carrier tape and the embossed portions of the carrier tape or the cover tape. Among electronic parts, semiconductors have low breakdown voltages due to minimization of elements and reduced thickness of oxide films that accompany the size reduction of semiconductors, and can therefore be easily destroyed by static electricity. Additionally, while electronic parts other than semiconductors are rarely destroyed by static electricity, they are generally becoming smaller and lighter in weight, so that they may adhere to the side of the cover tape due to static electricity when the cover tape is stripped, as a result of which they may not be able to be picked up properly, thereby reducing the efficiency of the mounting process.
For this reason, various cover tapes have been investigated for the purpose of preventing problems caused by static electricity. For example, in JP-B 3241220 (Patent Document 1), conductive carbon particles, a conductive powder of a metal oxide etc., or metal microparticles are mixed in the carrier tape and/or cover tape or coated thereon as means for preventing build-up of static electricity in the tape package. In the case of cover tapes, a metal oxide (such as tin oxide or zinc oxide) is generally mixed in the heat seal layer to ensure transparency.
Additionally, JP-A 2005-178073 (Patent Document 2) proposes a method for preventing build-up of static electricity on the surface of a cover tape by providing a charge transfer layer between the substrate layer and heat seal layer.    Patent Document 1: JP-B 3241220    Patent Document 2: JP-A 2005-178073